According to Wikipedia's article on Azad Kashmir:
Azad Jammu and Kashmir (Urdu: آزاد جموں و کشمیر Āzād Jammū̃ o Kaśmīr, translation: Free Jammu and Kashmir), abbreviated as AJK and commonly known as Azad Kashmir, is a nominally self-governing jurisdiction administered by Pakistan.
And further down in the Wikipedia article:
Azad Jammu and Kashmir (AJK) is a self-governing state under Pakistani control, but under Pakistan's constitution the state is informally part of the country. Pakistan is administering the region as a self-governing territory rather than incorporating it in the federation since the UN-mandated ceasefire. Azad Kashmir has its own elected President, Prime Minister, Legislative Assembly, High Court, with Azam Khan as its present chief justice, and official flag.
As for your question:
What I want to know is if Pakistan Occupied Kashmir is independent country or is it a integral part of Pakistan.
Wikipedia has another article on UN mediation of the Kashmir dispute. It ends with the Simla agreement, on which there is a different Wikipedia article. It notes the following major outcomes of the agreement:
Both countries will "settle their differences by peaceful means through bilateral negotiations". India has, many a times, maintained that Kashmir dispute is a bilateral issue and must be settled through bilateral negotiations as per Simla Agreement, 1972 and thus, had denied any third party intervention even that of United Nations.
The agreement converted the cease-fire line of 17 December 1971 into the Line of Control (LOC) between India and Pakistan and it was agreed that "neither side shall seek to alter it unilaterally, irrespective of mutual differences and legal interpretations". Many Indian bureaucrats have later argued that a tacit agreement, to convert this LOC into international border, was reached during a one-on-one meeting between the two heads of government. However, Pakistani bureaucrats have denied any such thing. This identification of a new "cease-fire line" by both the states has been argued by India as making United Nations Military Observer Group in India and Pakistan insignificant. As according to India, the purpose of UNMOGIP was to monitor the cease-fire line as identified in Karachi agreement of 1949 which no longer exists. However, Pakistan have a different take on this issue and both countries still host the UN mission.
As such, I think it's safe to say that it's an on-going dispute with no definitive answer. In practice, there is a self-governing state under Pakistani control (Azad Kashmir) and there is the Indian state Jammu and Kashmir. The latter used to have a special status under article 370 of the Indian constitution, but that status was revoked on the 5th of August 2019.
